Solar vs Generator?

Lots of new Airstream owners want to find ways to extend their camping time while “boondocking,” (off-grid camping, away from electrical hookups). So inevitably the question comes up: which is better, a generator or solar panels?

Generator AirstreamThe answer comes down to your needs. Generators are the most practical way to have enough power to run very high-wattage appliances like the air conditioner and microwave oven. If you must have air conditioning when not plugged in, you will have to use a generator, and it will need to be capable of at least 2,600 watts peak output, and preferably 3,000 watts.

However, if you can live without your air conditioner and microwave oven, solar panels become a very attractive option. Solar panels are silent, don’t require you to carry fuel, and are virtually maintenance free (other than washing them once in a while). They work without any intervention from you and can keep the batteries in your Airstream charged while it’s in storage.

A major difference is that solar panels only provide power to charge the batteries. They don’t directly power anything, although the batteries will of course power all of your 12-volt devices and can even power low-wattage 120-volt AC appliances like laptops and TVs using an inverter.

Most RV generators have on-board inverters so that they can provide 120-volt AC power directly to the Airstream, just like plugging in. This is convenient but most of the time the generator is producing far more power than you actually need.

If you want a generator primarily to recharge your batteries while camping off-grid, you can get the smallest generator possible. Even a small 1000-watt (rated) generator can typically produce far more power than the batteries will accept at any given time. The rest of the power is wasted, unless you are running the microwave or some other power-hungry AC appliance while the generator is running.

This means that the best time to use the generator is when power demand is high. It’s much easier to avoid using battery power by being plugged into the generator, than to try to recharge battery power later. Use the generator in the morning and evening when you are cooking and using lights and water pump, and the power needed will be supplied by the generator rather than coming from the batteries.

If you want to get a generator, do yourself and your neighbors a favor and get one of the quieter models specifically made for RV use. Both Yamaha and Honda make excellent products which have good reputations for reliability and quietness. If you borrow a “construction” generator from work on your weekend camping trip you will save some money but you won’t be popular when you fire it up—and the noise might detract from the peacefulness of your boondocking site, so what’s the point? Similarly, there are cheaper “knock off” brand generators on the market, but their quality is not up to the standards of the major brands.

Solar’s big advantage is in recharging batteries, so if extending your time at camp is your primary goal, they are the preferred option. Rather than pumping out large amounts of power in short time periods like a generator, solar provides a steady all-day charge will have a much better chance of getting your batteries up to 100%. It’s like the turtle and the hare. With batteries, slow and steady wins the race.

If you have both a generator and solar panels, use the generator when the batteries are heavily discharged (for an hour or so in the morning, for example) to get the bulk charge done quickly, and then let solar finish the job over the course of the day.

If you only have solar, keep in mind that during the morning and mid-day, moderately or heavily discharged batteries will probably accept every amp the panels can generate. Then the charging rate naturally slows down. If the sun is still shining at that point you have surplus power, and so that’s the time of day to plug in all of your rechargeable accessories like phones, cameras, laptops, etc. This strategy takes maximum advantage of the power being generated.

Sometimes people go with generators over solar because they are afraid they won’t have power on a cloudy day. Certainly clouds will drastically reduce the amount of power generated, but you’ll still get some. The solution is to add batteries so that the Airstream has enough power to bridge a cloudy day (or two) without a problem.

If you are considering adding solar panels, keep in mind that the solar panels should be sized to approximately match the capacity of the batteries in the Airstream. If the panels produce a lot more power in a typical day than the batteries can store, you’ll have wasted money on expensive panels. If the panels are too small, they might not produce enough power to keep the batteries charged, which can lead to short battery life if the trailer is not plugged in regularly (such as during long-term storage).

It’s hard to do an apples-to-apples comparison of generators and solar panels, because as you can see, they perform very differently. It’s even hard to pin down a cost for comparison, because the output of each option can vary widely. Quiet RV generators from Honda and Yamaha range from 1,000 watt units suitable for battery re-charging and small appliances, up to big 3,000 watt units to run the air conditioner. Solar panel systems (including battery banks) can run from 50 watts up (typically 200-400 watts will fit on the roof, plus more possible using portable panels), and the costs of an installed system are likewise varied. Keep in mind that comparing wattages is not useful since the solar panel runs whenever the sun shines, and the generator usually only runs for short times.

You’ll need to decide which option you prefer, and then talk to a solar installer, or shop generator prices. RV solar specialists are in many parts of the country (some are even mobile and will come to you) and they can help determine the optimal size of your battery bank and provide solar panels to match.

Either way, upgrading your Airstream to give you more boondocking time is a great advantage. It will open up new travel options for you and eliminate worries about running out of power when on a long trip or during storage.

For more, pick up your copy of Rich Luhr’s books, “The Newbies Guide To Airstreaming” and “Airstream Life’s (Nearly) Complete Guide To Airstream Maintenance” at the Airstream Life store.

How to improve your battery charging while boondocking

Nancy in Casa Grande, Arizona has questions about battery power:

“We are interested in upgrading the battery in our Airstream, and the converter to one that will charge via the generator better than the factory model. We want the battery to last longer when we dry camp, and have a converter that charges without running the generator for hours on end. The Xantrex was really overkill for us and the price for the amount of time we spend dry camping seemed a bit high. Is there a less high end unit available (we really don’t need a lot of the features)?”

Nancy, good question—and you’ve actually asked two separate questions. First, no matter what type of battery you use, it can only put out as much power as it can store. So to get more camping time when “off grid”, you need larger capacity batteries or more batteries (or both). Look at the “C/20” amp-hour rating of batteries—the higher, the better.

The trade-off will be increased weight, size, and expense, so think carefully about how much power capacity you need. Also consider where larger or more numerous batteries will fit in your Airstream. A professional solar consultant can be very helpful here.

Your second question was about the converter/charger. Upgrading the converter/charger won’t dramatically speed up the charge rate of the batteries. The battery is the primary limitation when it comes to charge rate. A “3-stage” charger will help a little, but you’ll still be running the generator for hours to get the battery full.

TriMetric 2020
TriMetric 2020

A better choice for frequent boondockers is a solar panel in conjunction with your generator. Use the generator for short “bulk” charges when the battery is low. Turn the generator off when the battery reaches about 80% or the charging rate slows down to a trickle. Then let the solar panel do the rest of the work over the course of the day.

You’ll need to install a good battery amp-hour monitor so you can see the battery charge rate, which will add about $200 to the tab, but for extended camping without power hookups it’s well worth the investment.